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For non-zero Froude numbers the shallow water equations are a hyperbolic system of partial differential equations. In the zero Froude number limit, they are of mixed hyperbolic-elliptic type, and the velocity field is subject to a divergence constraint. A new semi-implicit projection method for the zero Froude number shallow wa-ter equations is presented. This method enforces the divergence constraint on the velocity field, in two steps. First, the numerical fluxes of an auxiliary hyperbolic system are computed with a standard second order method. Then, these fluxes are corrected by solving two Poisson-type equations. These corrections guarantee that the new velocity field satisfies a discrete form of the above-mentioned divergence con-straint. The main feature of the new method is a unified discretization of the two Poisson-type equations, which rests on a Petrov-Galerkin finite element formulation with piecewise bilinear ansatz functions for the unknown variable. This discretization naturally leads to piecewise linear ansatz functions for the momentum components. The projection method is derived from a semi-implicit finite volume method for th